article: Every summer morning, I know I am going to my favourite place to volunteer and make a difference in someone's life just by being with him or her-----a summer school for children with autism . 
  By helping the kids read or do math, I am not only teaching important skills but also helping them feel like any other kid. There are many wrong ideas about autism. The kids I work with can think and feel. They need help only in certain areas.
  Of course, each kid is special. For example, some kids like to draw, and others like to sing.
  At the school, the kids learn through about 20 activities. These activities can help them learn skills they will need later in life.
  The very first day I volunteered, a boy came up to me, put his hand on my shoulder and said "Hello." From then on, I knew I could make a difference.
  Another boy loved to have me read books that can help him learn to read. Sometimes he could be encouraged to read a few words or sentences. Finally, one day during reading practice, he read nearly 220 words himself!
  Summer school is also a time for fun. Last summer, bagpipe players came to perform. Most of us had our hands over our ears because they were so loud. When they asked for a volunteer from the audience, one girl raise her hand as high as she could, got up on stage and even tried the bagpipes in front of everyone.
  Through these experiences, I realize that the challenges these kids face do not stop them from doing many amazing things. I'm teaching them, but they are teaching me as well.
question: What does the writer mainly talk about in the passage?
options: His teaching experience in a summer holiday How to make a difference in others' lives His experience as a volunteer in a special summer school What the life of the children with autism is like